1. Technical Field
The present invention relates to a shield connector used to connect shield wires.
2. Related Art
A shield wire is comprised of a covered conductor and a shield layer, constituted by a shield brading or the like, that are covered with an insulation sheath. In order to connect such shield wires, a shield connector is employed. A shield connector is comprised of male and female connectors adapted to be fitted to each other. Each connector has a housing that accommodates therein a connector terminal and a shield pipe to which a covered conductor and a shield layer of a shield wire are connected, respectively. The conductor extending through the connector is shielded from external electric field by the shield pipes.
FIGS. 6A, 6B, 7, 8A and 8B show by way of example a conventional shield connector comprised of male and female connectors 12 and 14 to which shield wires 10A and 10B are connected, respectively.
The male connector 12 includes a first housing 16 for receiving a male terminal 18 and a first shield pipe 20. The housing 16 is constituted by inner and outer housings 16a, 16b between which the shield pipe 20 is disposed. The shield pipe 20 may be inserted between the inner and outer housings 16a, 16b fabricated beforehand or may be formed integrally with the housings 16a, 16b by means of insert forming. A first shield wire 10A has its distal end portion whose insulation sheath 10s and insulating coating 10q are peeled off, so that a shield layer 10r and a covered conductor are exposed from the insulation sheath 10s and further a central conductor 10p is exposed from the insulating sheath 10q. The male terminal 18 is inserted into the inner housing 16a of the male connector 12 and retains a distal end of the covered conductor of the shield wire 10A, with the exposed central conductor 10p of the covered conductor crimped and connected to the male terminal 18.
Further, the male connector 12 has an elastic ring 22 made of silicon rubber or the like and press-fitted to the shield pipe 20. The elastic ring 22 has resiliency to electrically connect the shield layer 10r to the shield pipe 20, which layer extends from between the elastic ring 22 and the insulating coating 10q to a distal end face of the elastic ring 22 and which is folded back to the insulation sheath 10s. The folded-back end of the shield layer 10r is fixed to the insulation sheath 10s by means of a fastening ring 24 of the male connector 12. The male connector 12 further includes a wire seal ring 26 of silicon rubber or the like which is press-fitted to the outer housing 16b for water-tightly sealing between the shield wire 10A and the outer housing 16b, and a backup ring 28 of engineering plastic or the like which is fitted to an end of the outer housing 16b for preventing the wire seal ring 26 from being detached from the outer housing 16b. 
The female connector 14 is fabricated basically in the same manner as the male connector 12. In FIGS. 6A and 6B, reference numeral 30 denotes a second housing comprised of inner and outer housings 30a, 30b between which a second shield pipe 34 is disposed. Accommodated in the inner housing 30a is a female terminal 32 to which a central conductor 10p of a second shield wire 10B is crimped and connected. The outer housing 30b is formed at its intermediate portion with an inner tube 30c. A housing seal ring 36 is disposed on an outer periphery of the inner tube 30c. 
In the shield connector configured as mentioned above, the male and female connectors 12, 14 are fitted to each other as shown in FIGS. 6A and 6B, whereby the male terminal 18 is fitted to the female terminal 32 to establish electrical connection between central conductors 10p of the shield wires 10A, 10B that are individually connected to the terminals 18, 32. Furthermore, respective distal end portions of the shield pipes 20, 34 of the connectors 12, 14 are fitted to each other, whereby electrical connection is established between the shield layers 10r of the shield wires 10A, 10B individually connected to the shield pipes 20, 34. In addition, the outer housing 16b of the male connector 12 is fitted between the outer housing 30b of the female connector 14 and the housing seal ring 36, which water-tightly seals between the outer housings 16b and 30b. 
The conventional shield connector has a drawback that the covered conductor comprised of the central conductor 10p and the insulating coating 10q of the shield wire 10A is bent obliquely upward between the elastic ring 22 and a proximal end of the male terminal 18, whereas the covered conductor of the shield wire 10B is bent obliquely downward between the elastic ring 22 and a proximal end of the female terminal 32, as shown in FIGS. 6A and 7.
The reason why the covered conductors are bent will be explained. Both the male and female terminals 18 and 32 are generally fabricated by press-forming a thin metal plate. In the fabrication, a bottom face of each terminal serves as a reference face to provide the terminal with a proximal-end crimp portion and a distal-end fitting portion. The male and female terminals 18, 32 are substantially the same in the construction of their crimp portions, but differ from each other in the construction of their distal-end fitting portions. That is, the distal-end fitting portion of the male terminal 18 is formed into a plate shape, whereas the distal-end fitting portion of the female terminal 32 is configured to have elastic tongues to which the plate like distal-end fitting portion of the male terminal 18 is fitted. Thus, the female terminal 32 is larger than the male terminal 18 in a height measured from the bottom face to the top face of the distal-end fitting portion. For this reason, when the male terminal 18 is fitted to the female terminal 32, the bottom face of the female terminal 32 is located below that of the male terminal 18. Since, a vertical distance between the central axis at the proximal-end crimp portion and the bottom face of the terminal is substantially the same between the male and female terminals 18, 32, the proximal-end crimp portion of the female terminal 32 is located below that of the male terminal 18. Accordingly, the central axis U1 at the proximal-end crimp portion of the male terminal 18 (i.e., the distal end of the covered conductor of the first shield wire 10A) is positioned above the central axis V at the distal-end fitting portion of the male terminal 18, and the central axis U2 at the proximal-end fitting portion of the female terminal 32 (i.e., the distal end of the covered conductor of the second shield wire 10B ) is positioned below the central axis V. On the other hand, each of the first and second shield wires 10A, 10B is supported by the ring 22, etc. disposed in the shield pipe, so as to be aligned with the central axis V at the connector end.
As explained above, according to the conventional shield connector having the first and second shield pipes 20, 34 disposed coaxially with each other, the covered conductor of the first shield wire 10A at one end of the connector is positioned at the same height as the central axis V, with a distal end thereof positioned above the central axis V, so that the covered conductor is bent obliquely upward. On the other hand, the covered conductor of the second shield wire 10B at the other end of the connector is positioned at the same height as the central axis V, with a distal end thereof positioned above the central axis V, so that the covered conductor is bent obliquely downward. Resilient forces produced by the covered conductors that are bent in the above manner act to incline the distal ends of the male and female terminals 18, 32 obliquely upward and downward, and thus the distal-end fitting portions of the terminals 18, 32 may be deformed, causing inconveniences in electrically connecting shield wires through the terminals 18, 32.
An object of the present invention is to provide a shield connector which prevents or suppresses covered conductors of shield wires from being bent in the shield connector, thereby achieving reliable connection of the shield wires.
According to the present invention, there is provided a shield connector which includes a male connector having a male terminal to which a covered conductor of a first shield wire is connected, a first shield pipe to which a shield layer of the first shield wire is connected, and a first housing for accommodating therein the male terminal and the first shield pipe; and a female connector having a female terminal to which a covered conductor of a second shield wire is connected, a second shield pipe to which a shield layer of the second shield wire is connected, and a second housing for accommodating therein the female terminal and the second shield pipe, wherein, when the male and female connectors are fitted to each other, the male terminal is fitted to the female terminal and distal end portions of the first and second shield pipes are fitted to each other. In the shield connector, the improvement comprises that the first and second shield pipes are arranged such that an axis of the first shield pipe is positioned away from reference faces of the male and female terminals with respect to a central axis passing through distal-end fitting portions of the male and female terminals and an axis of the second shield pipe is positioned close to the reference faces with respect to the central axis, as viewed in a direction perpendicular to the axes of the first and second shield pipes.
As mentioned above, according to the conventional arrangement where the first and second shield pipes are arranged in alignment with the central axis passing through distal-end fitting portions of the male and female terminals, the first and second shield wires supported coaxially with the first and second shield pipes are aligned with the central axis, whereas distal ends of covered conductors of the first and second shield wires connected to proximal ends of the male and female terminals are positioned out of alignment with the central axis, and accordingly the covered conductors of the shield wires are bent.
On the contrary, according to the present invention, the axis of the first shield pipe is positioned away from the reference faces of the male and female terminals with respect to the central axis, and accordingly both the first shield wire and the distal end of the covered conductor thereof are positioned at substantially the same height on the axis of the first shield pipe, whereby the covered conductor of the first shield wire is prevented or suppressed from being bent. Furthermore, since the axis of the second shield pipe is positioned close to the reference faces of the male and female terminals with respect to the central axis, both the second shield wire and the distal end of the covered conductor thereof are positioned at substantially the same height on the axis of the second shield pipe, thereby preventing or suppressing the covered conductor of the second shield wire from being bent. As a result, the shield connector of the present invention can prevent or suppress deformation of the male and female terminals which would otherwise be caused by resilient forces produced by covered conductor subject to bending, establishing a satisfactory connection between the first and second shield wires through the shield connector.